An extrusion-based 3D printer is used to build a 3D model from a digital representation of the 3D model in a layer-by-layer manner by extruding a flowable modeling material. A filament of the modeling material is extruded through an extrusion tip carried by an extrusion head, and is deposited as a sequence of roads on a substrate in an x-y plane. The extruded modeling material fuses to deposited modeling material, and solidifies upon a drop in temperature. The position of the extrusion head relative to the substrate is then incremented along a z-axis (perpendicular to the x-y plane), and the process is then repeated to form a 3D model resembling the digital representation. Movement of the extrusion head is performed under computer control, in accordance with build data that represents the 3D model. The build data is obtained by slicing the digital representation of the 3D model into multiple horizontally sliced layers. Then, for each sliced layer, the host computer generates a build path for depositing roads of modeling material to form the 3D model.
In the printing process, the filament changes the material of the filament, thereby changing the final mechanical and aesthetic properties of the finished object. In some instances, polylactic acid (PLA) or acrylonitrile, butadiene, styrene (ABS) polymer or polyamides are used for filaments.
It is desirable for the filament to have a constant diameter (in some instances, 1.75 mm or 3 mm); otherwise, finely tuning the amount of material in the printed object is challenging. It is difficult to achieve a constant diameter for the filament, which is believed to depend on the characteristics of the polymer.
It is further desirable that the filament be printable, which, as the term “printable” is used herein, means the filament achieves appropriate adhesion with the plate and among the layers.